Air filter



FIG. 1 is a left front perspective view of an air filter showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a right front perspective view thereof; and,

FIG. 9 is a left bottom perspective view thereof. 

CLAIM We claim the ornamental design for an air filter, as shown and described. 